Background and purpose: Blood metal ion levels can be an indicator for detecting implant failure in metal-on-metal (MoM) hip arthroplasties. Little is known about the effect of bilateral MoM implants on metal ion levels and patient-reported outcomes. We compared unilateral patients and bilateral patients with either an ASR hip resurfacing (HR) or an ASR XL total hip replacement (THR) and investigated whether cobalt or chromium was associated with a broad spectrum of patient outcomes.

Patients and methods: From a registry of 1,328 patients enrolled in a multicenter prospective follow-up of the ASR Hip System, which was recalled in 2010, we analyzed data from 659 patients (311&thinsp;HR, 348 THR) who met our inclusion criteria. Cobalt and chromium blood metal ion levels were measured and a 21-item patient-reported outcome measures (PROMs) questionnaire was used mean 6 years after index surgery.

Mentions:
The metal ion concentrations and PROMs were obtained at a mean of 6 (2–11) years from index surgery. Whole blood samples were assessed by certified laboratories using standardized collection methods. The study cohort was divided into 2 groups, ASR HR and ASR XL THR. Each of these groups was further divided into 2 subgroups: patients with unilateral implants and those with bilateral implants (Figure 1). We used 7 ppb and 10 ppb as the metal ion threshold levels described for high-risk patients based on recent MoM follow-up algorithms (MHRA 2012, Kwon et al. 2014).

Mentions:
The metal ion concentrations and PROMs were obtained at a mean of 6 (2–11) years from index surgery. Whole blood samples were assessed by certified laboratories using standardized collection methods. The study cohort was divided into 2 groups, ASR HR and ASR XL THR. Each of these groups was further divided into 2 subgroups: patients with unilateral implants and those with bilateral implants (Figure 1). We used 7 ppb and 10 ppb as the metal ion threshold levels described for high-risk patients based on recent MoM follow-up algorithms (MHRA 2012, Kwon et al. 2014).

Background and purpose: Blood metal ion levels can be an indicator for detecting implant failure in metal-on-metal (MoM) hip arthroplasties. Little is known about the effect of bilateral MoM implants on metal ion levels and patient-reported outcomes. We compared unilateral patients and bilateral patients with either an ASR hip resurfacing (HR) or an ASR XL total hip replacement (THR) and investigated whether cobalt or chromium was associated with a broad spectrum of patient outcomes.

Patients and methods: From a registry of 1,328 patients enrolled in a multicenter prospective follow-up of the ASR Hip System, which was recalled in 2010, we analyzed data from 659 patients (311&thinsp;HR, 348 THR) who met our inclusion criteria. Cobalt and chromium blood metal ion levels were measured and a 21-item patient-reported outcome measures (PROMs) questionnaire was used mean 6 years after index surgery.